United States' Allyson Felix, second from right, crosses the finish line to win gold ahead of Jamaica's Shelly-Ann Fraser-Pryce, right, in the women's 200-meter final at the Olympic Stadium in London on Wednesday, Aug. 8, 2012.

Before the Olympics, Allyson Felix — for once — didn’t play to type. In track circles, Felix has a squeaky-clean reputation. She’s deeply religious, polite, and smiles often. She’s about as controversial as a corn muffin.

But in the lead-up to the London Olympics, Felix showed that she has a cold, calculating side. And because Felix got mean, she finally fulfilled her Olympic dream.

In her pet event, the 200-meters, Felix has won three world titles. But in the last two Olympic games, she finished second, each time behind Veronica Campbell-Brown of Jamaica. Those disappointments are now a distant memory. On Wednesday night at the Olympic Stadium, Felix crushed a stellar 200-meter field to win her first individual Olympic gold medal. “It’s a bit of a blur right now,” Felix said afterwards. Before the race, Felix remembered Beijing, where she crossed the finish line and broke down in front of her family. “Tonight, I saw them,” says Felix, “and it was just complete happiness.” Felix led a parade of American gold medalists on the track Wednesday night: Brittney Reese won the women’s long jump, and Aries Merrit took the 110-m hurdles title.

One crucial difference between London and Felix’s prior Olympic efforts: this time, she doubled up, competing in the 100-meter race as well as the 200. Felix had doubled-up at meets before, but mostly in the 200 and 400-meter events. Although Felix did not run the 400 in Beijing, she won gold in the 4 X 400 relay at those Olympics, But after last year’s world championships, in which she competed in both the 200, where she won bronze, and the 400, where she won silver, Felix decided to hone in on the shorter sprint.

How did the 100 help her in the Olympics? “I think it was huge for me,” says Felix. “I feel like going back to the 100, it made me aggressive.” Felix ran 10.89 seconds in the Olympic 100, a personal best, and finished fifth. She says that quick time “encouraged” her in next race. “I just knew that speed would help in the 200,” says Felix. “And I definitely think it did.” Running the 400, Felix said in a pre-race press conference, “really put me in a kind of rhythm, and it was hard to break out of it. So when I went to go run the 200, I just didn’t have my typical speed.”

Felix’s brother and agent, Wes, gives the 100 full credit for her sister’s gold. “She always loses the races in the first 60 meters,” says Wes. “If you look back at ‘04 and ‘08, Veronica has always been just too far ahead of her. And she’s trying to run her down, and she just runs out of real estate. So she knew she had to change the first 60 meters. And if she could come off the turn even, or in front, she was going to have a chance then. So I think when she really realized that and understood that, and her and Bobby [Kersee, Felix’s coach] got together and figured out how to make that happen in a race, I think that was all the difference.”

Running a full lap requires pacing. In the 200, there’s no time for any lulls. A runner like Michael Johnson, who won golds in both the 200 and 400 at the Atlanta Olympics, could adjust. Felix found out she couldn’t. Her elegant form may have helped cause her struggles. “I think my running style is a gift and a curse,” says Felix. “It looks very fluid, you know, it’s nice. But sometimes you have to get into that aggressive mode, and you need that quicker turnover. And I think that when people look at me, it always looks like I’m floating, and going slow.” The 400 caused complacency. “It was a really weird feeling,” she says. “Just to get to a spot, then realize you don’t have another gear. So for this year, staying with the sprint has just helped me to stay aggressive, and in that mode.”

So she ran the 100 at this year’s Olympic trials – and finished with a personal best, 21.69 seconds, in the 200. And though she was slower in the 200 Wednesday night – she ran a 21.88 — the 100-200 combo worked again in London. But Felix almost failed to qualify for the 100 at these Games. At the Olympic trials race, Felix and her training partner, Jeneba Tarmoh, fought for the third and final spot on the team. After both runners crossed the line, Tarmoh’s name flashed on the scoreboard, in third place. Felix congratulated Tarmoh, then sobbed. Tarmoh took a victory lap.

Later that night, however, track officials reversed the ruling. Tarmoh and Felix, in fact, had finished in a dead heat. A Keystone cop drama then unfolded, since track officials had no tie-breaker procedures on record. Finally, U.S.A Track and Field settled on a run-off.

There was thought, however, that Felix might cede the 100. “I think everyone just expected me to give up the spot, because lots of people, they know me, they know that I’m seen as this very nice girl,” says Felix. “So I think that was the thought, that it would be just automatic.”

Further adding fuel to the controversy, the photo finish judge of the 100-meter race, in an SI.com article, said that he stuck by his original decision: Tarmoh had beaten Felix. However, he was overruled, and the conspiracy machine went into overdrive. For example, did officials declare the race a dead heat because they wanted Felix, the higher-profile athlete, in the Olympics? USA Track and Field denied these charges. But once Tarmoh found out how the process unfolded, she unraveled. Tarmoh said she was “robbed,” and passed on the runoff. She was in no mental shape to race.

Why didn’t Felix help out a distraught friend, and give Tarmoh, who did not make the team in the 200, her spot? Well, we’re not talking about a county finals here. “This is the Olympics,” Felix said in London before her event. “This is not something that I started last year. It’s not an easy thing. I remember when I first came to Bobby, almost eight years ago, we sat in a Coco’s restaurant. And he asked me, ‘what did I want to do?’ What did I want to accomplish? I told him that at the Olympics, I wanted to run the 100, the 200, the 4 by 100, and the 4 by 400. And at that time, he was like ‘that’s a lot, but I think that we can do it.’ It was right then that we started training for it.”

“And I think that everyone sees this one moment on the track when you’re competing, and they forget that this is your lifestyle. This is what you sacrifice enormously. … It’s not just about me. It’s about Bobby and the time he invested in me. It’s about my parents and the sacrifices they made, my brother, the agents who are working with me, everyone who has invested their time in me.”

During the trials dustup, Felix talked to Jackie Joyner-Kersee, her coach’s wife, and the former Olympic gold medalist in the heptathlon and long jump. “She said you can’t give this up,” says Felix. “You’ve worked too hard.’” Felix and Tarmoh both insist that the runoff drama has no impact on their friendship. “We both deserved to fight for it,” says Felix. “For me, that was what it was all about. It wasn’t just thinking this is Jeneba, the person I train with that I care so deeply about. It was about … that conversation with Bobby and just a flood of emotions and everything coming up, and I just didn’t want to take it lightly.”

Even if Felix had lost the 200, she made the right call. After toiling for years, you have to seize what’s yours. Now, finally, Felix no longer carries Olympic failure down the track. “The moments that motivate me most are losing on the biggest stage,” Felix said after winning in London. “I don’t know if I would had success. Would it be the same? Would I push as hard? I said I would give all those world championship medals for the gold. Now I am able to just say that I embraced that journey. I embraced the defeats. Because that’s what pushed me all these years. And it just made tonight very, very sweet.”